Compiling c++ code with make

Question:

I'm trying to compile a C++ project using the following makefile code:

OBJS        = main.o src.o
SDIR        = ./src
IDIR        = ./include
BDIR        = ./bin/
ODIR        = $(BDIR)/obj


all: main

%.o: $(SDIR)/%.cpp $(IDIR)/%.h
    g++ -c -o $(ODIR)/$@ $(SDIR)/$<  -I $(IDIR)

main: $(OBJS)
    g++ -o $@ $^ -I $(IDIR)

When I try to compile the program, the following error appears in the terminal:

xxxx@zzz:$ make
g++    -c -o main.o main.cpp
main.cpp:2:17: fatal error: src.h: Arquivo ou diretório não encontrado
 #include "src.h"
                 ^
compilation terminated.
<builtin>: recipe for target 'main.o' failed
make: *** [main.o] Error 1

But the file 'src.h' exists and is inside the simple include. So I would like to know what is the reason for the error.

Answer:

Since your .obj is in a subdirectory you need to add that subdirectory as a prefix:

OBJS        = $(addprefix $(ODIR)/, main.o src.o)

The rule also needs to use the subdirectory:

$(ODIR)/%.o: $(SDIR)/%.cpp $(IDIR)/%.h

In the end the makefile looks like this:

SDIR        = ./src
IDIR        = ./include
BDIR        = ./bin
ODIR        = $(BDIR)/obj
OBJS        = $(addprefix $(ODIR)/, main.o src.o)

all: main

$(ODIR)/%.o: $(SDIR)/%.cpp $(IDIR)/%.h
    g++ -c -o $@ $<  -I $(IDIR)

main: $(OBJS)
    g++ -o $@ $^ -I $(IDIR)